Dry kiln



J. A. RANKIN July 21, 1931.

DRY KILN Filed July 28. 1927 3 Sheets-Sheet l July 21, 1931. J, RANK|N I 1,815,798

my KILN iiled July 28. 1927 I 3 Sheets-Sheet 2 run 3 Sheets-Sheet 3 J. A. RANKIN DRY KILN Filed July 28. 1927 r||||||| .nlllll I|||||||| 1 Ill July 21, 1931.

Patented July 21, 1931 UNITED STATES PATENT OFFICE JOSEPH A. RANKIN, OF SAMOA, CALIFORNIA, ASSIGNOR TO MOORE DRY KILN COM- PANY OF OREGON, A CORPORATION OF OREGON DRY KI'LN Application filed m 28, 1927. Serial m5. 208,946.

My invention relates to dry kilns generally,

and has for its main object the production of means for promoting the economical, efiicient and unlform drying of lumber in its manutacture for the trade.

In point of economy, my kiln is adapted to be operated at a material saving of driving power and of heat, by .reason mainly of a novel disposition of the fans and heating elements of a kiln, relatively to one another and to the drying stock.

In point of efficiency and uniformity of the drying operation, a material gain is effected through employment of a novel directness of application of the circulatory drying medium to the material to be dried.

What constitutes my invention will be hereinafter specified in detail and succintly defined in the appended claims.

In the accompanying drawings, in which my invention is illustrated in present preferred form of embodiment,

Figure I is a longitudinally vertical section of one end of one of my empty kilns and also charged with loads of stock to be dried.

Figure IV is a partial detail sectional view taken on the line IV-IV of Figure III.

Figure V is a horizontal sectional view taken as on the line V V of Figure III, and showing the end of kiln part of a double track as illustrated in Figure II, but with illustration omitted of the stock loads shown in Fi re III.

Re erring to the numerals on the drawing? 1 indicates a kiln comprising a structure 0 any desired form, size, and dimensions preferred. Said structure may be built of any suitable and preferred material, and may be of dimensions proper for the accommodation of one, two, or any number of series of stock loads which may be desired, and of correspondingly adequate drying equipment. Whatever be its capacity, the structure contemplated is such as to constitute a suitable housingfor a completly operative kiln.

In Figure III, y way of example, I show two stock loads 2 and 3 which are disposed in relative lateral disposition, and which represent an endwise succession of stock loads to suit the capacity of the drying chamber of the kiln. Each drying chamber may be made to accommodate two series of stock loads, as shown for example in said figure, or it may be enlarged so as to include additional series'of stock loads. On the other hand, the kiln may be restricted to a size suitable for the accommodation of one series,

or in other words, a single line of stock loads.

In any form of embodiment of my invention, the kiln 1 is preferably provided with cross girders 4 which may be disposed at suitable intervals apart, and .whose opposite ends are supported in the kiln side walls 5 and 6, respectively, as well as by suitable foundation supports, such, for example, as

columns 7.

The kiln 1, whatever be its capacity, is revided with terminal doors 9 and 10 0 dilnensions proper for the charge and discharge, respectively, of one or more series, as aforesaid of stock loads of lumber or other material, indicated, for example, by the numerals 2 and 3 in Figure III.

One characteristic feature of any embodiment of my invention consists inoperatively .p'osite sides of-the series of stock loads-two chambers 14 and 15, with which the fans 16 of said fan-installation are, .on their induction and eduction sides, respectively, in operative communication, the fans, as shown in said figure for example, being in direct comlocating an internal-fan system in either of 3 position of the fan installation in one corner' chamber on one side of the kiln, and the other into a suction chamber on the other side thereof.

Still another feature thereof, consists in compelling the respective currents of circulation to follow a course in which they make within the kiln but four turns, each at substantially right angles, thereby reducing resistance to circulation and consequently the power necessary to drive the fans. The limiting of the currents to four turns within the kiln is made possible by the dis of the kiln as aforesaid, and in directing the current of circulation in respect to each fan 16 in one right angled turn through the fan.

Each of the chambers 14 and 15 is closed at-the top by curtains 17 and 18 or other partitions, respectively, extending from the under side of the roof 19 substantially the entire length of the interior of the kiln in a horizontal line 20 disposed a little below the top of the series of stock loads 2 or 3, for instance, so as to cut off from air circulation the space above the same.

Each stock load is movably supported as by wheeled trucks 21 which travel on tracks 22 laid upon and'carried by the cross girders 4. The spaces between the girders are closed, respectively, by sections preferably made of concrete so as to constitute an intermediate floor 23. The floor 23 extends substantially the full length of the interior of the. kiln, but is denominated intermediate because of its relationship to the interior height of the kiln, and'to thef'chambers 14 and 15, subiairlitially as shown, for example, in Figure Each of the fans 16 of the fan system is provided in effect, with a fan chamber which ispreferably bounded on one end by a depending transverse vertical partition wall 24, in openings in which the fans are housed, 9 and is bounded on one side in the kiln illustrated by the adjacent side wall 6, as shown,

for example, in Figure III. On the side of the fan chamber opposite the kiln side wall 6 and .coextensivetherewith, a wall-section 25, having for each fan 16 an opening 26, is

provided as indicated in Figures I and II,

and as shown in detail in Figure IV. Be-

' tween the aforesaid kiln wall 6, for'example,

and the wall 25, the fan chambers, respectivel'y,*are further defined by transverse partition walls 27.

- Openings or throats28 in the intermediate floor 23 for free movement of the circulatory medium from the fan chambers for each cated at 30, whose function is either to direct air currents through the respective fan chamber upwardly through its throat 28, or, upon reversal of the fans 16, to deflect said currents in continuous circulation, in the opposite direction, that is to say, from said chamber 14 to the fan chambers of the proper fans 16, respectively, along lines of least resistance to the flow of said currents towards the chamber 15.

Also, preferably oblique deflectors 31, made as of concrete, are provided so as to extend, for example, from the upper portion of the wall 25 to. effect a juncture with the wall or floor 23 next adjacent to the chamber 14. Above the outer line of said juncture indicated at 33, an upstanding guard rail or barrier 84. extends upwardly so as to substantially close the space between the bottom of the superposed series of stock loads, for example, and the upper surface of the intermediate floor 23, with the effect of practically preventing leakage or short-circuiting of air underneath said loads. To that end, also, the deflectors 31 contribute, by causing the fans 16 when rotating in one direction to discharge air upwardly into the chamber 14 against the side wall, for example 6, of the kiln. Thereby, at its angle of reaction from the wall 6, said current, indicated by arrows in Figure III, is caused to impinge against the side of the'adjacent series of stock loads 3 well above the lower surfaces of said series. The intermediate floor 23 below the member 34 may be supported to advantage by the walls 25 and by the respective deflectors 31. -The longitudinal deflec- Y tor 31 deflects the circulating medium toward complishes the same result when flowing in the opposite direction on reversal. This is importantin connection with flat piling of lumber.

Somewhere in the space between the floor 11 and the intermediate floor 23, and preferably in substantially parallel relationship with the wall 25, are located heating units, for example heating coils 35, which afford radiating surface for any suitable and preferred type of heating system which may be employed.

In. kilns having capacity to accommodate only a single line of stock loads,.the assemblage of heating coils 35 is suflicient, but in those having greater capacity additional heating coils or units 36 will be placed between adjacent stock loads 2 and 3, as shown in Figure III, for effectively reconditioning the circulative heating medium after its passage through one series of loads to the loads next in series.

It is deemed unnecessary to describe herein any heating system in detail because my present invention doesnot demand the em-' ployment of a heating system of any particular type, but calls only for employment of any one preferred of many systems suitable for the purpose intended that are already in common use in the art of heating, or which may be hereafter devised.

The fans 16, being of any suitable number preferred, are mounted and fixed, preferably in equally spaced succession, on

a common shaft 37 which is revolubly carried as in journal pedestals 38, and which,

extending substantially the entire length of the kiln, is prolonged through the wall 40 of a basement chamber '41 within which chamber it is operatively connected with any suitable driving engine, for example an electric motor 42.

My invention comprehends a novel method of mounting thefans 16 on the shaft 37 in such a wa as to neutralize the respective end thrusts o the fans in combination, and thus eliminate a large amount of friction in the rotation of the fans by eliminating the me cessity for thrust bearings for the fan shaft 37 which otherwise would have to be provided.

Said method may be accomplished as follows. Should the kiln have six fans, for example, as illustrated in Figures I and II, they will be arranged by my invention on the shaft 37 in paired relationship one towards another. They will be disposed on said shaft on each side of the medial line of the kiln and with their respective pitches opposed.

The arrangement above described is given as the one at present preferred, but my invention contemplates the employement of any tion comprehends the lacing of the end fans of a series directly un er the end walls 9 and 10, respectively, of the kiln proper, and the provision of terminal extensions of the fan casings.

One extension, 44, tends towards the base ment chamber 41 as illustrated in Figure II,

1 and the other, '45, is disposed at the opposite end of the kiln, as shown in Figure I. Both 1 ably noncorrosive metal, and may be internal fan kilns to place the respective end fans within the kiln approximately four feet from the respective end walls of the kiln. One,of these fans, in such case, operates to blow the circulating medium or air away from one of the end walls, and makes it necessary in kilns of that description to divert the air to the end of kiln in order to give it proper circulation to those portions of the stock loads thatare near the doors. I In order to get such proper circulation it has been heretofore necessary to compel the air to almost reverse its course. This reversal being repeated throughout the kiln with respect to .all the fans, results in loss of efiiciency inthe kiln. The reason is that indirect air travel is effected by use of baflles or other devices for diverting the air currents, from which a static condition results with the effect of increasing the load on the motor or engine which drives the fans. My invention, in respect 'to the aforesaid terminal extensions of the fan casings, and the relative disposition thereto of the terminal fans, is not only applicable to the hereinbefore described fan system comprehending the location of fans within one corner of the kiln, but also to fan systems in which the fans are otherwise located, as, for exam le in medially located fan series, adapted for blowing air up the open middle portion of the kiln and down its sides, or up one or both sides of the kiln and down throughits middle portion. Attention is invited in this connection to special forms of fan housings 48, provided below the partitions 24.

My invention further comprehends the employment of. hollow inductor partitions 49 projecting horizontally from the wall 25 towards the wall 6. Each has an opening 50 on top and one 51 at one end, respectively, l

and theyare dis osed in the openings 28, communicating t rough their openings 50 v with the chamber 14 above, and through their openings 51 with the interior of the kiln at their junction with the wall 25. They may be constructed of any suitable material, prefer laced singly,- as illustrated in Figures LII III, and IV, or in groups. The purpose of their employment is to effect, by induced currents. .of air, additional air flow from the heating unit 35 into the interior body of the kiln. This device is in the nature of an economizer,

inasmuch as practically all the air throughout the kiln being in motion during the time the kiln is in operation, a portion will be .induced, without imposing additional fan load, to pass through the open cavities 51 of the inductor partitions 49, respectively, into the kiln and thus materially to increase the effectiveness of the circulation within the kiln.-

It should be understood, as of'course, that the kiln is provided with equipment of any usual or preferred means for functionating in such manner and to such ends asare common in dry kilns. Of said means there may be mentioned, by way of example, means for ventilating, for humidifying, or for promoting movements of the circulatory medium within the kiln, but these are mere details alreadyfamiliar in commonuse in the art. By way of specific example, the roof 19 of the kiln is shown as provided with damper ventilators 54, whose respective dampers 55 may be made operable from one point by a common shaft-56.

It may be observed, also, that the tracks 22 maybe, if desired, disposed longitudinally on an incline to the horizontal; but this, too, is only a well known detail for facilitating movement of stock loads from the intake to the outlet end of the kiln, and maybe employed or not as preferred.

The heating coils 36' may be, for instance, supported on columns 57 ranged in tiers on the floor 23 and below a roof-supportin beam 58, if such support of the roof 19 is eemed necessary.

Within the kiln, preferably along the corner thereof that is opposite that in which the fan installation already described is effected, I prefer to provide a fresh air duct extending from end to end of the kiln through the end walls thereof and opening at its ends through usual doors or dampers, not illustrated. The said. fresh air duct isconviently located in the corner of the'kiln, because thereby a single inclined wall60 penetrated at frequent intervals by ports 61, may be employed todefine it. The numeral 60 may be used to designate the duct itself as well as the wall which is a part of it and coextensive therewith.

The following is a brief description of the operation of my kiln. The intake door 9 of the kiln is in the charging operation opened, and the kiln is supplied with a complement of stock loads mounted, respectively on trucks, 21. After the kiln is charged, 0th the doors 9 and 10 are closed, heat is'supplied, both through the coils 35 and through the coils 36 if employed, and the shaft 37 is set in motion to rotate the fans 16.

The fans 16 being preferably disc fans of o the reversible type, the shaft 37 may be oper-' ated in either direction. If it be assumed that the fans are. rotated to make delivery of air upwardly through their respective throats 28,

such delivery will constitute thechamber 14 into a plenum chamber with the effect of thereby converting said chamber into a suction chamber which tends to cooperate With the plenum chamber 14 to promote positive air circulation in opposition to any resistance that may beinterposed by conditions of the atmosphere of the kiln to defeat it. A reversal of the direction of air circulation results in constituting the chamber 15 into the plenum chamber and the chamber 14 into the suction chamber. The currents of such circulation, in either direction, sweeping over the heated surfaces of the coils 35, through the .loads 3, for example, and thence directly over the surface of coils 36 through the laterally adjacent stock loads 2, if present, contribute to the drying operation of the kiln. It will therefore be seen that the air circulatingin one direction flows through the throat 28 so as to strike the deflective effect against the wall 6, while upon reversal of direction of flow of'the air through the throat 28 on opposite sides of the kiln, the air will be deflected against the wall 5. In other words, it will be seen that the air, in circulating in either direction, flows through the throat and strikes with deflective effect against the side wall of the kiln substantially at or near the center of the load. While it is preferred to employ the oblique deflector 31, it is tobe understood that this element is not essential, since any other .means may be employed for deflection of the circulatory currents throu h the throat to coact against the side wall 0 the kiln and to be deflected against the substantial center of the stock load in either direction of circulation,

a gain in efliciency maybe effected by varying the speed of the fans to meet'varying de-' mands in the dryingstages. This may be effected by any suitable means, such, for

example, as the use of'a multi-speed drivingmotor or engine.

The fresh air duct 60 may be used in the manner familiar in the art for supplying to the interior of the kiln outside air as needed to take the place of that drawn oflf as through the ventilators 54. i

WhatIclaimis: I 1. .In a dry kiln, the combination therewith of heating means therefor, and aninternal-fan system therein, with fan duct extensions beyond the end walls of the kiln at the opposite ends of said fan system, respectively, and in communication with said fan system. I,

2. In a dry kiln, the combination there with of heatmg means therefor and an internal fan system therein, with terminal fan duct extensions beyond the end walls of the kiln at the opposite ends of said fan system, respectively, and in communication with said fan system, the two end fans included in said fan s stem being disposed, as specified, substantlally under the end walls of the kiln respectively.

3. A dry kiln comprising within it the combination' of heating means, an intermediate floor dividing the interior of the kiln longitudinally so as to define longitudinally disposed openings at the opposite sides, respectively, for the'passage through them, respectively, of currents of air circulation, chambers defined upon opposite sides, respectively,by stock made loads provided within the kiln and made permeable to the passage of air, said chambers making communication with the said openings aforesaid, respectively, and an internal fan system consisting of a series of rotary fans on a shaft and a continuous fan duct assemblage having as one of its parts one of the side walls of the kiln and the said internal fan system in operative communication, respectively, with the said communicating openings and chambers. said fan duct including transverse and longitudinal deflector, said transverse deflectors receding away from the fan blast and said longitudinal deflectors deflecting circulating medium toward an adjacent side wall of the kiln.

' 4. In a dry kiln, the combination with an intermediate floor therein defining openings between its opposite sides and the adjacent sides of the kiln, respectively, and chambers on opposite sides of the kiln in operative communication with said openings, respectively defined by a series of stock-loads supported by said floor, of means for driving a current of air circulation through one of said openings and its appropriate chamber and a vertical guard rail on said floor adapted to substantially close the space between said floor and the bottom of the stock-loads.

5. Ina dry kiln, the combination with an intermediate floor therein defining openings between its opposite sides and the adjacent sides .of the kiln, respectively, and chambers on opposite sides of the kiln in operative comnrunication with said openings, respectively, defined by a series of stock-loads supported by said floor, of an internal-fan system comprising fans, a vertical guard rail on said .fioor adapted to substantially close the space between said floor and thebottom of the stock-loads, and an oblique deflector extending above each fan adapted to direct air discharge therefrom in a line above the top of said guard rail.

6. In a dry kiln, substantially rectangular in cross section, the combination with heating means therefor, and stock-load supporting means, of an internal-fan system consisting of a substantially continuous fan duct located in an interior corner of the kiln, and oblique deflectors adapted to discharge with deflecting effect air from the fan system against the inner face of one of the kiln walls.

7. In a dry kiln, substantially rectangular in cross section, the combination with heating means therefor, and stock-load supporting means of an internal-fan system consisting of a substantially continuous fan duct located in an interior corner of the kiln, and oblique deflectors adapted to discharge with deflecting effect air from the fan system against the inner f ce of one of the kiln walls, said fan system' comprising right hand fans and left hand fans disposed substantially at opposite ends of the kiln.

8. In a dry kiln, substantially rectangular in cross-section, the combination with heating means therefor, and stock-load supporting means of an internal-fan system consisting of a substantially continuous fan duct located in an interior corner of the kiln, and oblique deflectors adapted to discharge with deflecting effect air from the fan system against the inner face of one of the kiln walls, said fan system comprising right hand fans and left hand fans disposed substantially at opposite ends of the kiln, for producing a positive continuous current of transverse recirculation through the stock.

9. In a dry kiln, substantially rectangular in cross section, the combination with heating means therefor, and stock-load supporting means, of an internal fan system located in an interior corner of the kiln, said system being housed and in a continuous series of duets substantially the full length of the kiln employing one of the side walls of the kiln building as one side. of all fan inlet and outlet chambers, said fan ducts defined in part by transverse deflectors receding away from the fan blast and a substantially continuous longitudinal deflector deflecting circulatory medium toward the adjacent side wall of the kiln, means for directing currents of circulation therefrom in recirculation within the kiln and through the stock loads, and a plurality of heating means located, respectively, in direct communication with the fan system and in indirect communication therewith between adjacent stock loads. 10. A dry kiln comprising the combination therewith of heating means therefor and an intermediate-floor within the kiln for supporting stock-loads permeable to passage of air, said floor defining openings along its 0 posite sides for transverse circulation of air therethrough within the kiln, with an internal fan system adjacent to and in immediate operative communication with one of said openings and in indirect operative communication with the other of said openings, said internal fan system consisting of a series of rotary fans and housings therefor for producing positive circulation through said openings, said housings having longitudinal deflectors parallel to said openings, andd guard baflies above and below the stockloa s.

11. A dry kiln comprising the combination therewith of heating means therefor,

ing longitudinal deflectors parallel to said openings for deflecting circulatory medium toward the adjacent side wall of the kiln.

12. A dry kiln comprising the combination therewith of heating means therefor and an intermediate floor within the kiln for supporting stock-loads permeable to the passage of air, said floor defining openings along its opposite sides for transverse circulation of air therethrough within the kiln, and an internal fan system adjacent to and in immediate operative communication with one of said openings and in indirect operative communication with the other of said openings, said internal fan system consisting of a series of rotary fans and housings therefor for roducing positive circulation through said 0 ening's, said housings having transverse an transverse deflectors receding away from the fan blasti a 13. A dry kiln comprising the combination therewith of heating means therefor and an intermediate floor within the kiln for supporting stock-loads permeable to passage of air, said floor defining openings along its opposite sides for transverse circulation of air therethrough within the kiln, and an internal fan system adjacent to and in immediate operative communication with one of said openings and in indirect operative communication with the other of said openings, said internal fan system consisting of a serles of rotary fans and housings therefor for'producing positive circulation through said openings, said'housings having longitudinal deflectors parallel to said openings for deflecting circulatory medium toward the adjacent side wall of the kiln, said internal longitudinal deflectors, said fans being disposed at opposite ends of the kiln, and being of right and left hand pltch,

respectively.

14. A dry kiln comprising the combination therewith of heating means therefor and an intermediate floor within the kiln for supporting stock-loads permeable to the passage of air, said floor defining openings along its opposite sides for transverse circulation of air therethrough within the kiln, and an internal fan system adjacent to and in. immediate operative communication with one of said openings and in indirect operative communication with the'other of said openings, said internal fan system consisting of a series of rotary fans and housings therefor for producing positive circulation through said openings, said housings having transverse and longitudinal deflectors, said transverse deflectors receding away from the fan blast, said internal fans being of right and left hand pitch, respectively, and disposed at opposite ends of the kiln.

15. In a. dry kiln substantially rectangular in cross section, the combination therewith of heating means and stock-load supporting means, and an internal fan system located in an interior corner of the kiln and adapted to direct a current of circulation within the kiln by a change of. direction of its move ment through the fan system, said fan system consisting of a series of rotary fans and housing therefor for producing positive circulation through said openings, said housings having longitudinal deflectors parallel to the side walls of the kiln, and guard baflies below and above the stock loads.

- 16. In a dry kiln substantially rectangular in cross section, the combination therewith of heating means and stock-load supporting means, and an internal fan system located in an interior corner of the kiln and adapted to direct a current of circulation within the kiln by a change oftdirection of itsmovement through the fan system said fan system consisting of a series of rotary fans and housings therefor for producing positive circulation through said openings, said housings having longitudinal deflectors parallel to the side walls of the kiln and guard baflies below and above the stock loads, said longitudinal deflectors providing means for deflecting circulatory medium toward the adjacent side wall of the kiln. 17. In a dry kiln substantially rectangular in cross section, the combination therewith of heating means and stock load supportin means, and an internal fan system locate in an interior corner of the kiln and adapted to direct a current of circulation within the kiln b a change of direction of its more ment through the fan system, said fan system consisting of a series of rotary fans and housings therefor for producing positive circulation through said openings, said hous ings having longitudinal deflectors parallel to the side walls of the-kiln and guard b-aflies below and above the stock loads, said hous-' ings having transverseand longitudinalfde- .flectors, said transverse deflectors receding from the fan blast.

18. In a dry-kiln substantially rectangular in cross section, the combination therewith of heating means and stock-load supporting deflectors providing means .for deflecting circulatory medium toward'the adjacent side means,

wall of the kiln, said internal fans being of right and left hand pitch,.respectively, and. disposed at opposite ends of the kiln.

19. In a dry kiln substantially rectangular in cross section, the combination therewith of 'heating'ameans and stock load supporting an "an internal fan system located in an interior corner of the kiln and adapted to direct a current of circulation within the kiln by a change of direction of its movement through the fan system, said fan system consisting of a series of rotary fans and housings' therefor, for producing positive circula-' tion through said openings, guard baflles below and above the'stock loads, said housin having transverse and longitudinal deflectors, said transverse deflectors receding from the having a vertical guard 'baflie along the top edge. w

22. In a dry ln'ln, the combination with stoc-kload supporting means, a stockload thereon stacked-flat with lumber laid inlayers substantially edge to edge between stickers, said loads defining openings between the opposite sides and the adjacent sides of the.

kiln, respectively, and chambers on opposite sides ofthe kiln in operat-ive communlcation with said openings, respectively, of an internal fan system comprising a series of rotary fans mounted on a longitudinal shaft and housed in a series of fan ducts located.

in an interior corner of the kiln, said fan ducts having unobstructed openings, respectively, communicating with the adjacent SIdGS' of the kiln, respectively, at substantially right angles to eachother, and means substantially parallel to the axis of the fan and spaced from the wall of the kiln for deflecting currents of air circulation against the inner face of one of the kiln walls.

In testimony whereof, I nave hereunto set In hand.

' JOSEPH A. RANHN.

fan blast, said internal fans .being of right and left hand pitch, respectively, and dissaid fans being right hand and left hand, re-' spectively disposed at opposite endsof the kiln, said fans being housed in (a continuous duct having transverse deflectors receding away from the fan blast, said deflectors receding in opposite directions from the substantial center of the kiln toward its opposite ends.

21. In a dry kiln'substantially rectangular in cross section, the combination with heating means therefor and stock-load supporting means,'of an internal fan system located in an interior corner of the kiln comprising V a rotative shaft, a plurality of fans o n( said Sdfitft, and'a fan duct having an inlet. and outlet on two adjacent sides of the ln'ln' at right angles to each other, said inlet and outlet openings being formed by oblique surfaces forming two sidesof the inlet and outlet compartments, one of said oblique surfaces 

